Dear Thomas,
First of all, Thanks a lot for coming by and answering, I respect your
efforts in developing in libpruio!! I cant imaging how much work you must
have put in..! :-)
Well, second things is you mean to say if I use 8 ADCs I cant achieve
1.25Khz+ sample rate, Than should I use external ADC? would it be easier?
and to be frank I have plenty of doubts in the pruio construct and
pruio_config, I which are as follows:
- You said I have 183 cycle open delay - but where is it? I have made
everything 0 ( zero!!) you can have a look at option setting in line
bellow!!
- pruio_new(PRUIO_DEF_ACTIVE, 0, 0, 0)
- And in my pruio_config, I have made averaging to 0 (you can see
that as well). delay 0,
- pruio_config(io, 1, PRUIO_DEF_STPMSK , 0, 4)
So, is my configuration is wrong or the approach?
few queries with respect to your new example
- This is also for only 3 ADC channels, so if I extend it for 8, will
this one also become slow?
- I am going to "monitor" the inputs continuously, so I require
continuous stream of input, will this approach work?
- Its later part of my project but I saw u using system timer so asking
that I also want to time stamp the data with system time, so can it be done
here or should I do it later?
Sorry if my queries sound novice but I am new to this & I am felling
overwhelmed by the whole thing..!! :-)
I have been reading the processor TRM and PRU reference manual and I
petrified, its kind of ocean of information. ( it remind me of "The old man
& the sea"!! )
Sincerely,
Rathin
PS:
On Wednesday, September 30, 2015 at 11:35:25 PM UTC+5:30, TJF wrote:
>
> Hi Rathin!
>
> I didn't read all the stuff in the posts of this thread. But most of it
> seams irrelevant. Forget it.
>
> You're using libpruio. That's the only way to reach your target --> That's
> OK.
>
> You cannot reach 20 kHz sampling rate due to two reasons:
>
> - you're using default step configuration. This is 183 cycles open
> delay and avaraging 4. That means 183 + 1 + 4 x 14 cycles for each sample
> (@ 24 MHz) = 10 kHz per channel. Therefor maximum sampling rate for 8
> channels is 1.25 kHz.
> - you're using IO mode. The ARM CPU determines the sampling speed and
> your printf statement slows down the program execution, so you don't get
> the previous mentioned 1.25 kHz.
>
> In order to reach 20 kHz sampling rate you have to do
>
>
> 1. configure customized steps for fast sampling (ie. no open delay and
> no avaraging)
> 2. use either MM or RB mode to get accurate timing
>
> Either have a look at the triggers
> <http://users.freebasic-portal.de/tjf/Projekte/libpruio/doc/html/_cha_examples.html#SubSecExaTriggers>
>
> example (to use MM mode) or check out the following code (comming from an
> example named rb_file for next libpruio versions)
>
>
> /** \file rb_file.c
> \brief Example: fetch ADC samples in a ring buffer and save to file.
>
> This file contains an example on how to use the ring buffer mode of
> libpruio. A fixed step mask of AIN-0, AIN-1 and AIN-2 get configured
> for maximum speed, sampled in to the ring buffer and from there saved
> as raw data to some files.
>
> Licence: GPLv3
>
> Copyright 2014-2015 by Thomas{ dOt ]Freiherr[ At ]gmx[ DoT }net
>
> Thanks for C code translation: Nils Kohrs <nils[ dot ]kohrs{ AT }gmail[
> dOt ]com>
>
> Compile by: `gcc -Wall -o rb_file rb_file.c -lpruio -lprussdrv`
>
> \since 0.2.0.2
> */
>
> #include "unistd.h"
> #include "time.h"
> #include "stdio.h"
> #include "../c_include/pruio.h"
>
> //! The main function.
> int main(int argc, char **argv)
> {
> const uint32 tSamp = 123401; //!< The number of samples in the files
> (per step).
> const uint32 tmr = 5000; //!< The sampling rate in ns (5000 -> 200
> kHz).
> const uint32 NoStep = 3; //!< The number of active steps (must
> match setStep calls and mask).
> const uint32 NoFile = 2; //!< The number of files to write.
> const char *NamFil = "output.%u"; //!< The output file names.
> struct timespec mSec;
> mSec.tv_nsec=1000000;
> pruIo *io = pruio_new(PRUIO_DEF_ACTIVE, 0x98, 0, 1); //! create new
> driver
> if (io->Errr){
> printf("constructor failed (%s)\n", io->Errr); return 1;}
>
> do {
> if (pruio_adc_setStep(io, 9, 0, 0, 0, 0)){ // step 9, AIN-0
> printf("step 9 configuration failed: (%s)\n", io->Errr); break;}
> if (pruio_adc_setStep(io,10, 1, 0, 0, 0)){ // step 10, AIN-1
> printf("step 10 configuration failed: (%s)\n", io->Errr); break;}
> if (pruio_adc_setStep(io,11, 2, 0, 0, 0)){ // step 11, AIN-2
> printf("step 11 configuration failed: (%s)\n", io->Errr); break;}
>
> uint32 mask = 7 << 9; //!< The active steps (9 to 11).
> uint32 tInd = tSamp * NoStep; //!< The maximum total index.
> uint32 half = ((io->ESize >> 2) / NoStep) * NoStep; //!< The maximum
> index of the half ring buffer.
>
> if (half > tInd){ half = tInd;} // adapt size for small files
> uint32 samp = (half << 1) / NoStep; //!< The number of samples (per
> step).
>
> if (pruio_config(io, samp, mask, tmr, 0)){ // configure driver
> printf("config failed (%s)\n", io->Errr); break;}
>
> if (pruio_rb_start(io)){
> printf("rb_start failed (%s)\n", io->Errr); break;}
>
> uint16 *p0 = io->Adc->Value; //!< A pointer to the start of the ring
> buffer.
> uint16 *p1 = p0 + half; //!< A pointer to the middle of the
> ring buffer.
> uint32 n; //!< File counter.
> char fName[20];
> for(n = 0; n < NoFile; n++){
> sprintf(fName, NamFil, n);
> printf("Creating file %s\n", fName);
> FILE *oFile = fopen(fName, "wb");
> uint32 i = 0; //!< Start index.
> while(i < tInd){
> i += half;
> if(i > tInd){ // fetch the rest(no complete chunk)
> uint32 rest = tInd + half - i;
> uint32 iEnd = p1 >= p0 ? rest : rest + half;
> while(io->DRam[0] < iEnd) nanosleep(&mSec, NULL);
> printf(" writing samples %u-%u\n", tInd -rest, tInd-1);
> fwrite(p0, sizeof(uint16), rest, oFile);
> uint16 *swap = p0;
> p0 = p1;
> p1 = swap;
> }
> if(p1 > p0) while(io->DRam[0] < half) nanosleep(&mSec, NULL);
> else while(io->DRam[0] > half) nanosleep(&mSec, NULL);
> printf(" writing samples %u-%u\n", i-half, i-1);
> fwrite(p0, sizeof(uint16), half, oFile);
> uint16 *swap = p0;
> p0 = p1;
> p1 = swap;
> }
> fclose(oFile);
> printf("Finished file %s\n", fName);
> }
> } while(0);
> pruio_destroy(io);
> return 0;
> }
> Desription
>
> rb_file {#SubSecExaRbFile}
> -------
>
> \Item{Description}
>
> This file contains an example on how to use the ring buffer mode of
> libpruio. A fixed step mask of AIN-0, AIN-1 and AIN-2 get configured
> for maximum speed, sampled in to the ring buffer and from there saved
> as raw data to some files.
>
> \Item{Preparation}
>
> No preparation is required. Optionaly you can customize the number of
> samples, the sampling rate or the number of samples in the source
> code and recompile your version.
>
> \Item{Operation}
>
> Start the program by `./rb_file` and you'll see console output like
> ~~~{.txt}
> Creating file output.0
> writing samples 0-65534
> writing samples 65535-131069
> writing samples 131070-196604
> writing samples 196605-262139
> writing samples 262140-327674
> writing samples 327675-370202
> Finished file output.0
> Creating file output.1
> writing samples 0-65534
> writing samples 65535-131069
> writing samples 131070-196604
> writing samples 196605-262139
> writing samples 262140-327674
> writing samples 327675-370202
> Finished file output.1
> ~~~
>
> The program created two new files in the current folder, named
> output.0 and output.1. The files contain the raw data from the three
> ADC channels AIN-0 to AIN-2.
>
> \Item{Source Code}
>
> src/examples/rb_file.bas
>
> src/c_examples/rb_file.c
>
>
> BR
>
--
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